Extrusion International 4-2021

38 Extrusion International 4/2021 QUALITY CONTROL Plastics are produced in countless variants today. The most common is polyethylene. Modern processes mean that there are also different variations of this material to- day. Low-density polyethylene, or LDPE, produced using a high-pressure process, is one of them. Transformadora de Etileno A.I.E. (TDE) has three plants for the production of low density polyethylene (LDPE) in Spain. The annual capacity of LDPE is approximately 160,000 t/year. TDE focuses on continuous quality control and assurance in the ongoing production process in order to detect and optimise dynamic production fl uctuations at an early stage and in a relatively short sequence. For this reason, two OP5 measuring systems are already in use in two of three production lines. Various deviations in production have an impact on viscosity and can there- fore be monitored by online viscosity measurement using OP5. The continuous measurement of the Melt Index (MI) of polymer samples also allows a fi nal classi fi cation of the batch material. Save time and reduce costs: Due to the continuous mea- surement, real-time results can be visualised in 5 to 10 minutes via the touch panel with a data trend in 24/7 op- eration. This leads to considerable time savings compared to a manual ISO 1133 measurement. The permanent data logging makes it possible to intervene signi fi cantly in the production process and save costs. High reproducibility through OP-MFR measurement.: The OP5 MFR measurement is a method carried out by means of exact control of the melt fl ow in combination with a high-precision and self-developed melt pressure measurement. This method achieves a typical reproduc- ibility of +/- 1 % in comparison to the manual ISO 1133 measurement with +/- 5-10 % deviation. OCS Optical Control Systems GmbH www.ocsgmbh.com Effective Process Optimisation in the Production of LDPE by Means of Online Quality Control “Quality control has always been important to us. But we were not really aware at the beginning that we could also ensure a considerable process optimisation by means of the OP5. At fi rst, the measuring device delivered results that seemed irreal to us. This was solely due to the fact that even several daily laboratory measurements could not adequately re fl ect the dynamic changes in production. These variations only became visible through the short measuring interval of the automated OP5 online measurement. The continuous quality control with the use of the OP5 allows us to optimise the production process at any time and at the same time to fi nally classify our batchmaterial. The advantages such as the fully automatedmeasurement, the considerable time savings through the reduction of transition times and the high reproducibility through the OCS equipment, in comparison to the manual ISO1133 measurement, contribute to an effective process optimisation and reduction.“ David Cerra González, Quality Coordinator at Transformadora de Etileno A.I.E. (TDE), Spain OP5 OnlineMeasurement at customer site TDE, Spain OnlineMVRMeasurement with OP5 vs. Manual. Note: If theMFR value changes dynamically in production, small time intervals between the sampling of OP5 and laboratory measurement are suf fi cient to result high differences. The high fl uctuations are now shown by the highmeasuring rate of the online measurement of the OP5. (©OCS) Online MVR Measurement by OCS OP5 Vs. Manual Laboratory Measurement Time MVR–withOP5(online) MVR–manual in lab Value